The present invention relates generally to compositions of matter, apparatuses and methods useful in detecting, identifying, and addressing microorganisms present in commercial process systems.
The presence and growth of certain microorganism in commercial process systems is an ongoing challenge. Many of the various stages of commercial process systems contain a variety of conditions having different amounts of water, nutrients, heat, shelter, anchoring substrates, chemical conditions, and/or an absence of predators which often function as environmental niches suitable for colonization by all sorts of microorganisms. Population growth by these microorganisms often pose a number of problems including degrading process functions and fouling the end products.
One such problem is microorganism induced crust deposit formation. Crust is the accumulation on a surface of an item present in a commercial process system of a rigid solid composition comprising deposited organic and/or inorganic material. The crust can be secretions and/or colonies of microorganisms themselves. In particular crust can include or consist of the accumulation of one or more kinds of hard shelled and/or chitin bearing and/or coral organisms. Crust can have many negative impacts on systems such as decreased operational efficiency, premature equipment failure, loss in productivity, loss in product quality, and increased health-related risks. Worst of all crust must often be physically removed by scraping or other physical means and this requires expensive shut downs or disassembly of part or all of the process system.
Another problem microorganisms pose is through the formation of biofilms. Biofilms are layers of organic materials comprising microorganisms or exopolymeric substance secreted by microorganisms which aid in the formation microbial communities. Biofilms can grow on the surfaces of process equipment as well as in pools of fluid. These biofilms are complex ecosystems that establish a means for concentrating nutrients and offer protection for growth. Biofilms can accelerate crust, corrosion, and other fouling processes. Not only do biofilms contribute to reduction of system efficiencies, but they also provide an excellent environment for microbial proliferation of other microorganisms including pathogenic organisms. It is therefore important that biofilms and other fouling processes be reduced to the greatest extent possible to maximize process efficiency and minimize the health-related risks from such pathogens.
Several factors contribute to the extent of biological contamination and govern the appropriate response. Water temperature; water pH; organic and inorganic nutrients, growth conditions such as aerobic or anaerobic conditions, and in some cases the presence or absence of sunlight, etc. can play an important role. These factors also help in deciding what types of microorganisms might be present in the water system and how best to control those microorganisms. Proper identification of the microorganism is also crucial to responding appropriately. Differences regarding whether the microorganisms are plants, animals, or fungi, or if they are planktonic or sessile determines how effective various biocontrols will be. Because different microorganisms induce different problems, proper identification is crucial to properly remediating unwanted microbial effects. Finally because chemically caused problems cannot be remediated with biocides, it is also necessary to identify which problems have non-biologically based origins.
Standard techniques typically used to monitor process systems include standard plate count techniques. These techniques require lengthy incubation periods and do not provide adequate information for pro-active control and prevention of problems related to microbial growth. More recently, adenosine triphoshphate (ATP) measurements have been used as a means of pro-active control. However, the reagents are costly and small volumes are sampled from large water systems. While it is possible to quantify microbial activity in a sample with the use of the ATP assay, the reaction is unable to discriminate between ATP that is produced by one type of microorganism compared to another and it does not detect organisms that are viable but inhibited. Another disadvantage is that this method cannot be used to determine microbial contribution to sheet defects because most organisms are not viable following exposure to the heat of the dryer section. Data collection is also infrequent, leading to significant gaps in data. Therefore, this approach provides limited information on the status of microorganisms in the system of interest. In addition, these approaches are typically used to monitor planktonic bacteria. Although in some cases, surfaces might be swabbed and analyzed in order to quantify biofilm bacteria. These approaches are very tedious and time-consuming.
Dissolved oxygen (DO) probes have been used to measure microbial activity in fluids, as it is well known that microbial activity and aerobic metabolism leads to a decrease in dissolved oxygen concentrations. U.S. Pat. Nos. 5,190,728 and 5,282,537, disclose a method and apparatus for monitoring fouling in commercial waters utilizing DO measurements. However, the approach requires the use of nutrient additions to differentiate biological from non-biological fouling and there is no mention of how the probe is refreshed for further measurements after the probe surface has fouled. In addition, the approach disclosed requires a means of continuously supplying oxygen.
The standard Clark style electrochemical DC) probe has many limitations such as: chemical interferences (H2S, pH, CO2, NH3, SO4, Cl−, Cl2, ClO2, MeOH, EtOH and various ionic species), frequent calibration and membrane replacement, slow response and drifting readings, thermal shock, and high flow requirements across membranes. A new type of dissolved oxygen probe, which has recently been made commercially available by a number of companies (e.g., HACH, Loveland, Colo.), overcomes nearly all of these limitations so that DO can be measured on-line in process waters. This new DO probe (LDO) is based on lifetime fluorescence decay where the presence of oxygen shortens the fluorescence lifetime of an excited fluorophore. The fluorophore is immobilized in a film at the sensor surface and the excitation is provided with a blue LED. U.S. Pat. Nos. 5,698,412 and 5,856,119 disclose a method for monitoring and controlling biological activity in fluids in which DO is measured in combination with pH and/or ORP (oxidation-reduction potential) to measure transitions in metabolic behavior, specifically related to nutrient/substrate depletion.
Conventional plating techniques and oxidant residuals may indicate adequate biocide dosing and control of microbial growth, while deposition, defects and breaks remain prevalent. There is a clear need to provide more accurate information regarding microbial growth and biofilm formation in industrial systems. Quantitative PCR techniques allow for rapid analysis of sheet defects, felts, process water samples, etc. to determine the contribution of microorganisms to quality issues. This new approach has been demonstrated to allow for a more proactive diagnosis of problems leading to improved machine efficiency and product quality.
Thus it is clear that there is clear utility in novel methods and compositions for the proper identification of microorganisms present on in commercial process systems. The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is “Prior Art” with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 CFR §1.56(a) exists.